- This topic has 2 replies, 2 voices, and was last updated 9 years, 9 months ago by
.
- Posts
Hi.
We are using a SA44B as a backend in our educational radio telescope interferometer, operating at 1.4 GHz. The SA44B is controlled from a Linux PC, using CUSBSA API and we have found that the spectrum has a noise that has a sinusoid shape, with ~200 kHz between peaks. We first blamed our amplifiers but after testing with a noise generator, we found that it is the SA44 who produces this effect which can be also seen with a 50 ohm load at the input. Funny thing is that we don´t see this when using Spike. We have tried with different BW and FFT values but no change. Any hint on what to do to eliminate the noise? (image attached).
Regards
JuanHello Juan,
I attached an image of the device in the Spike software exhibiting the same shape as your software. I used 1 dB per div while your plot was 0.2 dB per div. The shape you are seeing is the shape of the IF band, the result of any filters and the RF path. The RF gain/attenuation is going to affect this shape as well as the frequency. Different start/stop frequencies will change the RF path of the input.
I hope this clarifies and validates what you are seeing.
Regards,
A.J.
You must be logged in to reply to this topic.